Apparatus for Cleaning a Fiber Suspension for a Papermaking Process

ABSTRACT

An apparatus for cleaning a fiber suspension for papermaking of foreign substances contained therein, such as sand, metal parts, glass splinters, bark fragments and the like, by using a tubular, vertically aligned housing, which is constructed with an inlet for the introduction of the fiber suspension into this housing under pressure, also provided at its lower end with an outlet for discharging the foreign substances contained in the fiber suspension and at its upper end with an outlet for leading off the fiber suspension freed of the foreign substances. In this case, at least a portion of the housing, or the lower housing parts, or at least a casing that encapsulates the lower housing parts, are produced from a transparent or a see-through material, in particular from a transparent or a see-through plastics material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. §119, of Austrian patent application A 1163/2007, filed Jul. 23, 2007; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention:

The present invention relates to an apparatus for cleaning a fiber suspension for papermaking of foreign substances contained therein, such as sand, metal parts, glass splinters, bark fragments and the like, by using a tubular, vertically aligned housing, which is constructed with an inlet for the introduction of the fiber suspension into the housing under pressure. The housing is provided at its lower end with an outlet for discharging the foreign substances contained in the fiber suspension and at its upper end with an outlet for leading off the fiber suspension freed of the foreign substances.

For papermaking, use is made of suspensions containing pulp fibers which, at the beginning of a wire section, are sprayed on to a wire belt over the width of the latter. In order to be able to rule out functional disruptions, in particular blockages of the feed lines to the spray nozzles and the spray nozzles, the fiber suspension must not contain any kinds of foreign substances, such as sand, metal parts, glass splinters, bark fragments and the like.

In order to clean a fiber suspension in the necessary way, a separating apparatus is known, by means of which the foreign substances contained in the fiber suspension are removed. This known apparatus comprises a vertically aligned tubular housing which is constructed with a connection at the side, through which the fiber suspension is introduced into its interior under pressure, flowing in circular movements in this housing. In this case, on account of the centrifugal forces effected because of these flows, the foreign substances which are heavier than the pulp fibers, such as sand, metal parts, glass splinters, bark fragments and the like, move radially outward, which means that they reach the inner wall of the housing and slide downward along the latter. By contrast, the pulp fibers, which are lighter than the foreign substances, remain in the radially inner region of this housing, moving upward in circular movements. At its lower end, the housing is constructed with an outlet, through which the foreign substances are led out of the housing. At its upper end, the housing is constructed with a further outlet, through which the fiber suspension freed of the foreign substances is led off.

Due to the fact that the foreign substances move along the inner wall of the housing, the inner wall is subjected to intense abrasion. Ultimately, this leads to the housing wall being broken through, meaning that the apparatus becomes unserviceable. In order to prevent the fiber suspension from being able to flow out in an uncontrolled manner in the event of such a break-through, in known apparatuses of this type the housing is constructed in its lower region with a casing, by which it is enclosed. By means of occasional inspection of the interior of this casing, it is possible to determine whether it is empty, in which case it is concluded that the housing does not have any break-through, or whether it contains a fiber suspension, which is the case when a break-through has occurred in the housing. As a result, this housing or the affected housing part is replaced by a new housing or by a new housing part.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an apparatus for cleaning a pulp suspension in a papermaking process which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which renders it possible to check the housing wall in a simpler way to see whether it still has a sufficient thickness so that there is no danger of break-through or whether, because of the abrasions, the thickness of the housing wall is already so low that there is a danger of break-throughs, for which reason the housing or a housing part must be replaced.

With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for cleaning a fiber suspension in a papermaking process of foreign substances (e.g., sand, metal parts, glass splinters, bark fragments, etc.). The novel apparatus comprises:

a tubular, vertically aligned housing formed of a lower housing part and an upper housing part;

said housing being formed with an inlet for introducing the fiber suspension with foreign substances into said housing under pressure;

said housing having a lower end formed with an outlet for discharging therefrom the foreign substances after removal from the fiber suspension, and an upper end formed with an outlet for discharging therefrom the fiber suspension freed of the foreign substances;

wherein said lower housing part has an exterior wall formed, in portions thereof or entirely, of a see-through material.

The term “see-through” as used herein encompasses any characteristic that allows visual inspection through the exterior wall. Specifically, the viewing window, or the entire wall may be translucent, transparent, or entirely clear.

In other words, the objects of the invention are achieved in that the housing or lower housing parts, or portions thereof, and/or a casing encompassing the lower housing parts, is or are produced from a transparent or a see-through material, in particular from a transparent or a see-through plastics material.

On account of the translucency or transparency of or the ability to see through the wall of the housing or of the housing parts, their thickness can be determined by occasional inspection, the housing or the affected housing part then being replaced when the thickness falls below a lower value at a point. In this case, it is not absolutely necessary to provide the housing with a casing. In this way, considerable savings are achieved.

If, in spite of this, the housing is constructed with at least one casing in its lower region, then at least the casing is produced from a transparent or see-through material. In that case, the housing part inside the casing may be produced of a non-see-through material, i.e., an opaque material.

In accordance with further, advantageous variations of the invention, the exterior wall of the lower housing part—either the housing itself or the surrounding casing—is formed of a transparent plastics material. Advantageously, the see-through portion of the outermost wall is formed of transparent polyurethane or of glass-clear polycarbonate. In other words, the housing or the lower housing parts and/or the casings that may possibly be provided are preferably produced from a transparent polyurethane. As an alternative to this, the housing or the lower housing parts and the casings that may possibly be provided are produced from a glass-clear polycarbonate.

If the housing is provided with the at least one casing in its lower region, then at least the casing is produced from a transparent or see-through material. The housing walls inside the casing may then be produced of a non-see-through material, i.e., an opaque material.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in apparatus for cleaning a fiber suspension for papermaking, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a vertical, or axial, section through a first exemplary embodiment of an apparatus according to the invention; and

FIG. 2 is a similar view showing a second exemplary embodiment of an apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, the apparatus according to the invention has a vertically aligned tubular housing, which comprises three housing parts 1, 2, and 3 arranged one above another and joined to one another. The first housing part 1 is constructed with an inlet opening 10 at the side, through which a fiber suspension containing foreign substances is introduced into the interior of the housing under pressure. In this housing part 1 there is a guide shield or baffle 11 running spirally, by which the fiber suspension introduced is made to flow circularly by forcing it into a vortex flow. Underneath the first housing part 1 is the second housing part 2, which tapers conically toward the bottom. Furthermore, in its radially inner region, the first housing part 1 is constructed with a pipe 12, which projects into the second housing part 2 and which extends upward, towards an outlet opening 20 formed at its geodetically upper end.

Furthermore, the second housing part 2 is adjoined by the third housing part 3, which located underneath it, likewise tapers conically toward the bottom and is constructed with an outlet opening 30 at its lower end. All the housing parts 1, 2 and 3 or, in any case, the housing parts 2 and 3 are produced from a transparent or see-through material. They are produced, for example, from transparent polyurethane or from glass-clear polycarbonate. Seals are provided between the individual housing parts 1, 2 and 3, so that their interior is sealed off with respect to the outside.

The mode of action of this apparatus is as follows:

A fiber suspension containing foreign substances, such as metal parts, glass splinters, bark fragments and the like, is introduced into the interior of the first housing part 1 under pressure through the inlet opening 10. A circular flow is imparted to this fiber suspension by the guide shield 11. Because of the centrifugal forces occurring in the fiber suspension as a result, the foreign substances contained in said suspension, which have a greater weight than the pulp fibers, move radially outward, which means that they reach the inner walls of the housing parts 2 and 3 and slide downward along the latter, leaving the housing through the outlet opening 30. By contrast, the fiber suspension freed of foreign substances moves upward in the central region of the housing parts 1, 2 and 3, reaching the outlet opening 20 through the pipe 12.

Since the housing parts 2 and 3 are produced from a transparent or from a see-through material, it is possible to determine at any time whether their walls are still sufficiently thick to be able to rule out the danger of break-throughs. If, by contrast, the thickness falls below a lower limiting value, the affected housing part is replaced by a new housing part. In this way, firstly undesired operational interruptions are avoided and secondly, as a result, cost savings are achieved, since the housing parts can be constructed without casings.

The exemplary embodiment illustrated in FIG. 2 differs from the exemplary embodiment according to FIG. 1 in that the housing parts 2 and 3 are constructed with casings 21 and 31, which have openings that can be sealed off by plugs 22 and 32 and which are produced from a transparent or a see-through material. That is, here, the casings 21 and 31 form the exterior wall of the lower part (2, 3) of the housing. As a result, it is also then not necessary to carry out a replacement when the thickness of the housing walls has fallen below the minimum value, since a break-through which may occur can be seen immediately, whereupon the necessary replacement can be made.

It will be understood that, in the second exemplary embodiment of the apparatus, both of the housing parts 2 and 3 may be formed from an opaque material. The casings 21 and 31, on the other hand, must be formed to be transparent, or at least translucent. This allows a ready inspection as to whether or not the housing parts 2 and/or 3 have suffered a breakthrough so that pulp suspension is able to spill. 

1. An apparatus for cleaning a fiber suspension in a papermaking process of foreign substances, comprising: a tubular, vertically aligned housing formed of a lower housing part and an upper housing part; said housing being formed with an inlet for introducing the fiber suspension with foreign substances into said housing under pressure; said housing having a lower end formed with an outlet for discharging therefrom the foreign substances after removal from the fiber suspension, and an upper end formed with an outlet for discharging therefrom the fiber suspension freed of the foreign substances; wherein said lower housing part has an exterior wall formed, in portions thereof or entirely, of a see-through material.
 2. The apparatus according to claim 1, wherein said exterior wall of said lower housing part is formed of a transparent plastics material.
 3. The apparatus according to claim 1, wherein said lower housing part is formed of a transparent plastics material.
 4. The apparatus according to claim 1, wherein said lower housing part is formed with a casing enclosing an inner housing, said casing defining said exterior wall of said lower housing part.
 5. The apparatus according to claim 4, wherein said casing is formed of a see-through material at least in portions thereof.
 6. The apparatus according to claim 5, wherein said casing is formed of transparent polyurethane.
 7. The apparatus according to claim 5, wherein said casing is formed of glass-clear polycarbonate.
 8. The apparatus according to claim 5, wherein said inner housing is formed of a see-through material.
 9. The apparatus according to claim 1, wherein said lower housing part is formed of transparent polyurethane.
 10. The apparatus according to claim 1, wherein said lower housing part is formed of glass-clear polycarbonate.
 11. The apparatus according to claim 1, wherein said housing is formed of transparent polyurethane.
 12. The apparatus according to claim 1, wherein said housing is formed of glass-clear polycarbonate. 